New counter-terrorism units have been working at Australia's two largest airports since last week and had already intercepted a person of interest, the prime minister said today.

Tony Abbott said the units operating at Sydney and Melbourne Airports would soon be introduced at all Australian international airports to monitor the movements of travellers on security watch lists. Biometric screening of passengers will also be introduced at all airports.

"I'm advised that these new units have already intercepted at least one person of interest," Abbott told Parliament. "This government will do I'm sure this Parliament will do everything that is reasonably necessary to keep our country safe."

The Australian Customs and Border Protection Service today did not immediately supply details of the person of interest, or say if charges had been laid.

Sky News television reported that a man was prevented from flying with his family from Melbourne to Lebanon this week and was detained for questioning.

The Australian government is giving high priority to reducing the domestic terrorism threat created by homegrown extremists who travel to Syria and Iraq to fight.

Australia and the United States will raise at the United Nations General Assembly in September the need for governments to cooperate against the common threat.

Abbott conceded this month that the nation's border security was not good enough after a second suspected jihadist flew to the Middle East using a brother's passport.

A 19-year-old Sydney man slipped out of the country, but was detained on arrival in the United Arab Emirates and deported. A notorious terrorist left Sydney in a similar security breach in December last year.

The government this month proposed tough new counter-terrorism laws as well as USD 590 million in additional resources over four years to help intelligence and law enforcement agencies cope with the scores of Australians who return home after committing terrorist acts overseas.

Some Islamic leaders argue Muslims, a minority of 500,000 in Australia's population of 23 million, were being unfairly targeted.

David Irvine, director general of the Australian Security Intelligence Organisation, Australia's top spy agency, told the National Press Club today that 60 Australians were fighting in Iraq and Syria for the al-Qaida offshoots Islamic State and Jabhat al-Nursa, also known as the Nusra Front. He said another 15 Australian fighters had been killed, including two young suicide bombers.